Adaptive tooling assembly

ABSTRACT

A fixture and a method of operating the fixture are disclosed for repositioning a workpiece disposed on the fixture to correct an offset between the centerline of the workpiece and an indexing position on the fixture. The fixture includes one or more linear actuators that linearly move vacuum grippers on their outboard ends into contact with surfaces of the workpiece. Vacuum is applied to the vacuum grippers, which enables the vacuum grippers to grip the surfaces of the workpiece. The linear actuators are driven to reposition the workpiece on the fixture to reduce the offset between the two below a threshold value. When in position, the fixture secures the workpiece in place for subsequent machining operations that may be performed on the workpiece.

FIELD

This disclosure relates to the field of manufacturing, and inparticular, to tooling fixtures that hold a workpiece during a machiningprocess.

BACKGROUND

In manufacturing, a workpiece often undergoes various machiningprocesses, such as cutting, boring, routing, etc. It is desirable torigidly hold the workpiece in a fixed position during the machiningoperations to prevent vibration, chatter, and/or flexing of theworkpiece in order to reduce the possibility of machining errors.Further, it is desirable to rigidly hold the workpiece in a fixedposition without introducing a pre-load on the workpiece, which may alsointroduce machining errors during the machining operations. Furtherstill, it is desirable to automate the alignment of the workpiece on thefixture to preclude a labor-intensive shimming process in order tocorrectly align the workpiece on the fixture. Thus, improvements infixture designs are an ongoing goal in the art.

SUMMARY

A fixture and a method of operating the fixture are disclosed forrepositioning a workpiece disposed on the fixture to correct an offsetbetween the centerline of the workpiece and an indexing position on thefixture. The fixture includes one or more linear actuators that linearlymove vacuum grippers on their outboard ends into contact with surfacesof the workpiece. Vacuum is applied to the vacuum grippers, whichenables the vacuum grippers to grip the surfaces of the workpiece. Thelinear actuators are driven to reposition the workpiece on the fixtureto reduce the offset between the two below a threshold value. When inposition, the fixture secures the workpiece in place for subsequentmachining operations that may be performed on the workpiece. Beingsemi-automatic in nature in its repositioning, the fixture replaces atime-consuming manual shimming process that would often be used toensure the workpiece is properly positioned on the fixture prior tomachining the workpiece. The fixture therefore supports, repositions,and secures the workpiece during a machining process, providing atechnical benefit of improving the set-up time and labor typically usedto machine workpieces.

One embodiment comprises a tooling fixture that includes a base member,a gripper assembly, and a controller. The gripper assembly includes alinear actuator coupled to a side of the base member and having anoutboard end that is linearly movable by the linear actuator. Thegripper assembly further includes a vacuum gripper located at theoutboard end of the linear actuator and a sensor. The sensor measures adistance to a surface of a workpiece disposed on the base member. Thecontroller calculates an offset between an indexing position on the basemember and a centerline of the workpiece based on a distance to thesurface of the workpiece. The controller moves the vacuum gripperrelative to the side of the base member in contact with the surface ofthe workpiece utilizing the linear actuator. The controller applies avacuum to the vacuum gripper to grip the surface of the workpiece, andrepositions the workpiece on the base member using the linear actuatoruntil the offset is less than a threshold value.

Another embodiment comprises a tooling system that includes a pluralityof tooling fixtures and a controller. The tooling fixtures are disposedon a common indexing line and hold a workpiece along its length. Each ofthe tooling fixtures includes a base member and a gripper assembly. Thegripper assembly includes a linear actuator coupled to a side of thebase member that has an outboard end that is linearly movable by thelinear actuator. The gripper assembly further includes a vacuum gripperlocated at the outboard end of the linear actuator and a sensor. Thesensor measures a distance to a surface of a workpiece disposed on thebase member. The controller calculates a deflection of a centerline ofthe workpiece with respect to the common indexing line on the toolingfixtures based on a plurality of distances measured by the sensors,operates the linear actuators to linearly move the vacuum grippersrelative to the sides of the base members into contact with the surfacesof the workpiece, and reposition the workpiece on the base membersutilizing the linear actuators until the deflection is less than athreshold value.

Another embodiment comprises a method of operating a tooling fixture.The method comprises loading a workpiece on a tooling fixture, whereinthe tooling fixture comprises a base member, a linear actuator coupledto a side of the base member and having an outboard end that is linearlymovable by the linear actuator, a vacuum gripper located at the outboardend, and a sensor located on the side of the base member that isconfigured to measure a distance to a surface of the workpiece disposedon the base member. The method further comprises calculating an offsetbetween an indexing position on the base member and a centerline of theworkpiece based on a distance measured to the surface of the workpieceutilizing the sensor. The method further comprises linearly moving thevacuum gripper relative to the side of the base member into contact withthe surface of the workpiece utilizing the linear actuator and applyinga vacuum to the vacuum gripper to grip the surface of the workpiece. Themethod further comprises repositioning the workpiece on the base memberutilizing the linear actuator until the offset is less than a thresholdvalue.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments or may be combined in yetother embodiments, further details of which can be seen with referenceto the following description and drawings.

DESCRIPTION OF THE DRAWINGS

Some embodiments are now described, by way of example only, and withreference to the accompanying drawings. The same reference numberrepresents the same element or the same type of element on all drawings.

FIGS. 1-3 depict a fixture for supporting, repositioning, and securing aworkpiece in place in illustrative embodiments.

FIG. 4 is a flow chart of a method of operating a fixture to support,reposition, and secure a workpiece in place in an illustrativeembodiment.

FIGS. 5-7 depict additional details of the method of FIG. 4 inillustrative embodiments.

FIGS. 8-15 depict the fixture of FIGS. 1-3 at different operationalstates in illustrative embodiments.

FIG. 16 depicts a tooling system in an illustrative embodiment.

FIG. 17 depicts a deflected centerline of the workpiece of FIG. 16 in anillustrative embodiment.

FIG. 18 depicts a corrected centerline for the workpiece of FIG. 16 inan illustrative embodiment.

FIG. 19 is a block diagram of the fixture of FIGS. 1-2 in anillustrative embodiment.

FIG. 20 is a flow chart illustrating an aircraft manufacturing andservice method in an illustrative embodiment.

FIG. 21 is a schematic diagram of an aircraft in an illustrativeembodiment.

FIG. 22 depicts a fixture for supporting, repositioning, and securing aworkpiece in place in another illustrative embodiment.

FIGS. 23-26 depict the fixture of FIG. 21 at different operationalstates in illustrative embodiments.

FIG. 27 is a block diagram of the fixture of FIGS. 21-26 in illustrativeembodiments.

DETAILED DESCRIPTION

The figures and the following description illustrate specific exemplaryembodiments. It will be appreciated that those skilled in the art willbe able to devise various arrangements that, although not explicitlydescribed or shown herein, embody the principles described herein andare included within the contemplated scope of the claims that followthis description. Furthermore, any examples described herein areintended to aid in understanding the principles of the disclosure are tobe construed as being without limitation. As a result, this disclosureis not limited to the specific embodiments or examples described below,but by the claims and their equivalents.

FIGS. 1-3 depict a tooling fixture 100 for supporting, repositioning,and securing a workpiece 200 in place in illustrative embodiments. Inparticular, FIG. 1 is an isometric view of fixture 100, FIG. 2 is across-sectional view of fixture 100 along cut lines 1-1, and FIG. 3depicts a plurality of fixtures 100 used to hold workpiece 200.Generally, fixture 100 operates as a holding fixture or tooling fixturethat supports workpiece 200 during one or more machining operations thatmay be performed on workpiece 200. Some examples of the machiningoperations that may be performed on workpiece 200 include cuttingoperations, drilling operations, grinding operations, boring operations,reaming operations, milling operations, reaming operations, etc.

In the embodiments described herein, workpiece 200 comprises any type ofstructure or component that may form part of a larger assembly. Forexample, workpiece 200 may comprise a component of an aircraft, such asa spar of a wing for the aircraft. Although workpiece 200 will berepresented in the present disclosure as having a particular size,shape, and orientation, workpiece 200 may have a different size, shape,or orientation in other embodiments.

In this embodiment, fixture 100 includes a base member 102 having a topsurface 104, a bottom surface 105 that opposes top surface 104, andsides 106-107 that oppose each other. Extending from sides 106-107 ofbase member 102 are a pair of linear actuators 108-109 that areconfigured to extend their respective outboard ends 114-115 towards andretract their respective outboard ends 114-115 away from sides 106-107of base member 102. During operation of fixture 100, linear actuators108-109 extend their outboard ends 114-115 away from sides 106-107 andcontact surfaces of workpiece 200 in order to reposition workpiece 200with respect to base member 102, and also to secure workpiece 200 inplace on fixture 100. Fixture 100 is designed to support, reposition,and secure workpiece 200 in place during machining operations, whilelimiting the preload that may be applied to workpiece 200 in order toprevent machining errors.

Referring to FIGS. 1-2, linear actuator 108 extends and retractsoutboard end 114 along axis 110 to move a contact member 112 located atoutboard end 114 of linear actuator 108 either toward side 106 or awayfrom side 106. Side 106 may be referred to as a first side in someembodiments. Located proximate to outboard end 114 of linear actuator108 is a vacuum gripper 116, which is configured to apply a vacuum tosurface 232 of workpiece 200 in order to secure workpiece 200 in placewith respect to linear actuator 108. In like manner, linear actuator 109extends and retracts its outboard end 115 along axis 111 to move acontact member 113 located at outboard end 115 of linear actuator 109either toward side 107 or away from side 107. Side 107 may be referredto as a second side in some embodiments. Located proximate to outboardend 115 of linear actuator 109 is a vacuum gripper 117, which isconfigured to apply a vacuum to surface 233 of workpiece 200 in order tosecure workpiece 200 in place with respect to linear actuator 109.Contact members 112-113 may have different shapes in other embodiments,or may be omitted in some embodiments. Further, axis 110-111 may becoincident in some embodiments or offset from each other. Collectively,linear actuator 108, contact member 112, and vacuum gripper 116comprises a gripper assembly 122 (e.g., a first gripper assembly in someembodiments). Collectively, linear actuator 109, contact member 113, andvacuum gripper 117 comprises a gripper assembly 123 (e.g., a secondgripper assembly in some embodiments).

During operation of fixture 100, a pair of sensors 118-119 (see FIG. 2)measure distances to surfaces 232-233 of workpiece 200 while linearactuators 108-109 translate vacuum grippers 116-117 towards/away fromsurfaces 232-233. With regard to FIG. 2, sensor 118 measures a distance202 to a flange 208 of workpiece 200 and sensor 119 measures a distance203 to a flange 209 of workpiece 200.

In some embodiments, fixture 100 includes one or more variable pressuregrippers 120 (see FIG. 1), which may apply a vacuum and/or a pressure tosurface 216 of workpiece 200 that is in contact with top surface 104 ofbase member 102. For example, during operation of fixture 100, variablepressure grippers 120 may apply a vacuum to surface 216 of workpiece 200(e.g., using vacuum source 228 of FIG. 2) in order to secure workpiece200 in place with respect to fixture 100. During a repositioningprocess, fixture 100 may utilize variable pressure grippers 120 to applya pressure to surface 216 of workpiece 200 (e.g., using pressure source230 of FIG. 2) in order to “float” surface 216 of workpiece 200 on topsurface 104 of base member 102. This allows linear actuators 108-109 tomore easily reposition workpiece 200 with respect to base member 102 byreducing the sliding friction between top surface 104 of base member andsurface 216 of workpiece 200.

Although fixture 100 has been illustrated with a particular number oflinear actuators 108-109, variable pressure grippers 120, and sensors118-119, fixture 100 may include any number of linear actuators 108-109,variable pressure grippers 120, and sensors 118-119 in otherembodiments.

Referring to FIG. 2 in particular, base member 102 may be mounted to astand 204 along bottom surface 105 of base member 102, which allowsworkpiece 200 to be elevated for access by a robotic end mill 210. Inthis embodiment, robotic end mill 210 includes one or more robotic arms212 that include an end effector 214. Robotic end mill 210 utilizes endeffector 214 to perform machining operations on workpiece 200, includingany of the machining operations previously described. In the embodimentillustrated in FIG. 2, workpiece 200 includes a web 206 and flanges208-209 that extend away from web 206. In this configuration, workpiece200 may comprise a spar for a wing of an aircraft.

As discussed previously, it was typical in the prior art to manuallyshim spars prior to performing machining operations on the spars inorder to ensure that the spars were positioned correctly on the workstands. Correctly positioning the spars on the work stands is importantin order to ensure that any machining operations performed on the sparsare performed accurately, as the accuracy of the machining operationsdepends on an accurate placement of the spars on the work stands.

In FIG. 2, fixture 100 is used to reposition workpiece 200 on basemember 102 to ensure that an indexing position 218 of base member 102 isaligned with a centerline 220 of workpiece 200. In some embodiments,indexing position 218 is a centerline of base member 102. Repositioningworkpiece 200 may be performed in response to how workpiece 200 isloaded on fixture 100 and/or in response to fabrication variations inthe dimensions of workpiece 200. In this embodiment, the operation offixture 100 is automated by a controller 222, although in otherembodiments, fixture 100 is controllable by other computing devices.

Controller 222 in this embodiment includes a processor 224 that iscommunicatively coupled to a memory 226. Processor 224 comprises anycomponent, system, or device that performs the functions describedherein for controller 222, including the activities described foroperating fixture 100. Processor 224 includes any hardware device thatis able to perform functions, and may include electronic circuits,optical circuits, or combinations of electronic and optical circuits.Processor 224 may include one or more Central Processing Units (CPU),microprocessors, Digital Signal Processors (DSPs), Application-specificIntegrated Circuits (ASICs), etc. Some examples of processors includeINTEL® CORE™ processors, Advanced Reduced Instruction Set Computing(RISC) Machines (ARM®) processors, etc.

Memory 226 includes any hardware device that is able to store data,including instructions for processor 224. Memory 226 may compriseelectronic circuits, optical circuits, magnetic circuits, orcombinations of electronic, optical, and magnetic circuits. Memory 226may include one or more volatile or non-volatile Dynamic Random-AccessMemory (DRAM) devices, FLASH devices, volatile or non-volatile StaticRAM devices, hard drives, Solid State Disks (SSDs), etc. Some examplesof non-volatile DRAM and SRAM include battery-backed DRAM andbattery-backed SRAM.

As discussed previously, vacuum grippers 116-117 may be supplied withvacuum by a vacuum source 228 when vacuum grippers 116-117 are incontact with surfaces 232-233 of workpiece 200. The vacuum applied byvacuum grippers 116-117 allow vacuum grippers 116-117 to grip workpiece200. For example, vacuum gripper 116 may be supplied with vacuum byvacuum source 228, thereby gripping surface 232 of flange 208 whenvacuum gripper 116 is in contact with surface 232. In like manner,vacuum gripper 117 may be supplied with vacuum by vacuum source 228,thereby gripping surface 233 of flange 209 when vacuum gripper 117 is incontact with surface 233. With workpiece 200 gripped in this manner,linear actuators 108-109 translate their outboard ends 114-115 alongtheir axis 110-111 either towards or away from their sides 106-107 ofbase member 102 in order to reposition workpiece 200 on fixture 100.

In some embodiments, multiple fixtures 100 may be used to supportworkpiece 200, depending on the dimensions of workpiece 200, asillustrated in FIG. 3. In FIG. 3, stands 204 are omitted for clarity andthe spar-like structure of workpiece 200 is more clearly identifiable.

FIG. 4 is a flow chart of a method 400 of operating a fixture tosupport, reposition, and secure a workpiece in place in an illustrativeembodiment, and FIGS. 5-7 depict optional steps for method 400. Further,FIGS. 8-15 are cross-sectional views of fixture 100 along cut-lines 1-1during different transitional states.

Method 400 will be described with respect to fixture 100, althoughmethod 400 may be implemented by other fixtures, not shown. The steps ofmethod 400 are not all inclusive, and method 400 may include othersteps, not shown. Further, the steps of method 400 may be performed inan alternate order.

Prior to loading workpiece 200 onto fixture 100, outboard ends 114-115of linear actuators 108-109 are retracted towards their respective sides106-107 in order to ensure that contact members 112-113 and/or vacuumgrippers 116-117 are not damaged as workpiece 200 is loaded onto fixture100 (see FIG. 8). In FIG. 8, workpiece 200 is loaded onto fixtured 100such that centerline 220 of workpiece and indexing position 218 of basemember 102 are not coincident (see step 402). Rather, centerline 220 ofworkpiece and indexing position 218 of base member 102 have offset 802that is non-zero and in particular, is larger than a threshold value.Such a non-zero offset 802 is due to the imprecise loading process ofworkpiece 200 on fixture 100 and/or due to dimensional variations inworkpiece 200 from one part to another part.

Processor 224 utilizes sensor 118 in order to measure distance 202 tosurface 232 of workpiece 200. Using distance 202, processor 224calculates offset 802 between centerline 220 of workpiece 200 andindexing position 218 of base member 102 (see step 404). For instance,memory 226 of controller 222 may store pre-defined dimensional data forworkpiece 200, which may be used by processor 224 to calculate offset802 based on the relationship between distance 202 and the pre-defineddimensional data for workpiece 200.

Offset 802 include both a displacement value and a direction ofdisplacement that depends on the frame of reference. In the followingdiscussion, the frame of reference is fixture 100, and in particularindexing position 218 of fixture 100. In FIG. 8, the direction of offset802 of centerline 220 is to the left of indexing position 218, althoughthe direction of offset 802 of centerline 220 may be to the right ofindexing position 218 in other embodiments.

In response to calculating offset 802, processor 224 operates one ormore of linear actuators 108-109 to extend their vacuum grippers 116-117towards surfaces 232-233 of workpiece 200 (see step 406). Processor 224may selectively operate one or more linear actuators 108-109 in order toreposition workpiece 200 on fixture 100 based on the direction of offset802. For example, processor 224 may selectively operate linear actuatorson a common side depending on the direction of offset 802 of workpiece200 on fixture 100. With offset 802 of centerline 220 being left ofindexing position 218 as illustrated in FIG. 8, processor 224 may electto operate linear actuator 108 alone in order to reposition workpiece200 on fixture 100 and/or may elect to operate both linear actuators108-109 in combination (e.g., by operating them in differentcombinations of extension and retraction after their vacuum grippers116-117 have gripped workpiece 200).

For the following discussion, FIGS. 9-10 will illustrate the use oflinear actuator 108 by itself for repositioning workpiece 200 on fixture100, while FIGS. 11-15 will illustrate the use of linear actuators108-109 in combination for repositioning workpiece 200 on fixture 100.

In response to calculating offset 802 and selecting linear actuator 108,processor 224 extends outboard end 114 of linear actuator 108 asillustrated in FIG. 9 in the direction of arrow 902, thereby movingvacuum gripper 116 into contact with surface 232 of workpiece 200. Withvacuum gripper 116 in contact with surface 232, processor 224 directsvacuum source 228 to apply a vacuum to vacuum gripper 116 (see step408). For example, processor 224 may operate one or more valves (notshown) to apply vacuum source 228 to vacuum gripper 116. With vacuumapplied to vacuum gripper 116, vacuum gripper 116 grips surface 232 ofworkpiece 200, although step 408 may be optional when a grip ofworkpiece 200 is not necessary (e.g., when linear actuator 108 canreposition workpiece 200 on fixture 100 without a grip on workpiece200).

Processor 224 continues to extend outboard end 114 of linear actuator108 in the direction of arrow 902 to move workpiece 200 in the directionof arrow 1002, as illustrated in FIG. 10. As processor 224 continues toextend outboard end 114 of linear actuator 108 in the direction of arrow902, workpiece 200 continues to move in the direction of arrow 1002until offset 802 is less than a threshold value, thereby effectivelyrepositioning workpiece 200 on fixture 100 as illustrated in FIG. 11(see step 410). With workpiece 200 repositioned on fixture 100,processor 224 may then extend outboard end 115 of linear actuator 109 inthe direction of arrow 1202 as illustrated in FIG. 12 to extend vacuumgripper 117 until vacuum gripper 117 contacts surface 233 of workpiece200, and apply a vacuum to vacuum gripper 117 to secure workpiece 200 tofixture 100. With workpiece 200 secured to fixture 100, robotic end mill210 (see FIG. 2) may utilize end effector 214 to perform one or moremachining operations on workpiece 200.

In an optional embodiment, processor 224 may lock one or more linearactuators 108-109 in place in response to repositioning workpiece 200 onfixture 100 (see step 502 of FIG. 5). The process to lock one or morelinear actuators 108-109 in place may depend upon the type andconstruction of linear actuators 108-109. For example, if linearactuators 108-109 operate using mechanical screws to extend theiroutboard ends 114-115 either towards or away from their respective sides106-107, then a locking mechanism may secure the screws from rotation inorder to lock linear actuators 108-109 in place. In another example, iflinear actuators 108-109 utilize hydraulics to extend their outboardends 114-115 either towards or away from their respective sides 106-107,then one or more hydraulic valves (not shown) may be closed to maintaina hydraulic pressure on linear actuators 108-109 in order to lock linearactuators 108-109 in place.

In another optional embodiment, processor 224 may apply a positivepressure to variable pressure grippers 120 prior to repositioningworkpiece 200 on fixture 100 (see step 602 of FIG. 6). For instance,processor 224 may operate one or more valves (not shown) to couplepressure source 230 to variable pressure grippers 120 in order to“float” surface 216 of workpiece 200 on top surface 104 of base member102 using a film of air, thereby reducing the sliding friction betweensurface 216 of workpiece 200 and top surface 104 of base member 102.

In another optional embodiment, processor 224 may, in response torepositioning workpiece 200 on fixture 100, apply a vacuum to variablepressure grippers 120 (see step 702 of FIG. 7) in order to secureworkpiece 200 in place on fixture 100. For instance, processor 224 mayoperate one or more valves (not shown) to couple vacuum source 228 tovariable pressure grippers in order to grip surface 216 of workpiece200, thereby preventing workpiece 200 from moving relative to fixture100. With workpiece 200 secured to fixture 100, robotic end mill 210(see FIG. 2) may utilize end effector 214 to perform one or moremachining operations on workpiece 200.

As discussed previously, processor 224 may operate linear actuators108-109 in combination in order to reposition workpiece 200 on fixture100, which is illustrated in FIG. 13. In FIG. 13, processor 224 extendsoutboard end 114 of linear actuator 108 in the direction of arrow 1302and extends outboard end 115 of linear actuator 109 in the direction ofarrow 1304 until their respective vacuum grippers 116-117 contactsurfaces 232-233 of workpiece 200. With vacuum grippers 116-117 incontact with their respective surfaces 232-233, processor 224 appliesvacuum source 228 to vacuum gripper 117 and optionally, vacuum gripper116 to grip their respective surfaces 232-233. In order to repositionworkpiece 200 using linear actuators 108-109 in combination, workpiece200 is moved in the direction of arrow 1404 as illustrated in FIG. 14,with processor 224 extending outboard end 114 of linear actuator 108 inthe direction of arrow 1302, and processor 224 retracting outboard end115 of linear actuator 109 in the direction of arrow 1402. With vacuumapplied to vacuum gripper 117, linear actuator 109 is able to gripsurface 233 and pull workpiece 200 in the direction of arrow 1304,thereby operating in cooperation with linear actuator 108. Processor 224continues to operate linear actuators 108-109 as illustrated in FIG. 14until offset 802 is reduced below a threshold value, as depicted in FIG.15. Any of the previously described optional steps of method 400 mayalso apply to the embodiments that utilize linear actuators 108-109 incombination.

Although fixture 100 has generally been describes in isolation, atypical embodiment utilizes multiple fixtures 100 that operatecooperatively to support, reposition, and secure workpiece 200 in placeas illustrated in FIG. 3. For example, fixtures 100 as illustrated inFIG. 3 may be separated into different zones, and operated independentlyin order to reposition workpiece 200 on fixtures 100.

FIG. 16 depicts a tooling system 1600 in an illustrative embodiment.FIG. 16 depicts a top view of workpiece 200 and fixtures 100 asillustrated in FIG. 3, with a plurality of fixtures 100 aligned witheach other on a common indexing line 1602 along a length 1601 ofworkpiece 200. In some embodiments, indexing line 1602 is coincidentwith a centerline of base members 102 of fixtures 100. In thisembodiment, fixtures 100 are organized into different zones 1604-1606,and are zone controllable by controller 222. Although only one fixture100 is illustrated in each of zones 1604-1606, any number of fixtures100 may be included in zones 1604-1606.

In this embodiment, processor 224 utilizes sensors 118-119 in fixtures100 to measure a plurality of distances 202-203 to surfaces 232-233 ofworkpiece 200, and calculates a deflection of workpiece 200 with respectto common indexing line 1602 of fixtures 100.

FIG. 17 depicts (although exaggerated) a deflection of a centerline 1702of workpiece 200 for purposes of discussion. Using the measurementinformation supplied by fixtures 100 in zones 1604-1606, processor 224operates linear actuators 108-109 of fixtures 100 independently, foreach of zones 1604-1606, to reduce the deflection of centerline 1702 ofworkpiece 200 below a threshold value. For instance, processor 224 mayoperate fixture 100 in zone 1604 to reduce distance 202 below athreshold value, in order to reduce the deflection of centerline 1702 inzone 1604 below a threshold value. In like manner, processor 224 mayoperate fixture 100 in zone 1605 to reduce distance 203 below athreshold value, in order to reduce the deflection of centerline 1702 inzone 1604 below a threshold value. Similarly, processor 224 may operatefixture 100 in zone 1606 to reduce distance 202 below a threshold value,in order to reduce the deflection of centerline 1702 in zone 1605 belowa threshold value. The result of these individual actions for each ofzones 1604-1606 is to reduce the deflection of centerline 1702 such thatit more closely represents the view in FIG. 18.

FIG. 19 depicts a block diagram of fixture 100 in an illustrativeembodiment. In this embodiment, fixture 100 includes base member 102,having top surface 104 that contacts and supports a spar 1902 for a wingof an aircraft, and a bottom surface 105 that may be coupled to stand204. Base member 102 has a side 106 (e.g., a first side) and side 107(e.g., a second side). Coupled to side 106 are one or more linearactuators 108, which have an outboard end 114 coupled to one or morevacuum grippers 116. A contact member 112 may also be coupled tooutboard end 114. Vacuum grippers 116 and/or contact member 112 areconfigured to contact surfaces of spar 1902 in response to a linearmovement of linear actuators 108. In like manner, coupled to side 107are one or more linear actuators 109, which have an outboard end 115coupled to one or more vacuum grippers 117. A contact member 113 mayalso be coupled to outboard end 115. Vacuum grippers 117 and/or contactmember 113 are configured to contact surfaces of spar 1902 in responseto a linear movement of linear actuators 108. In this embodiment,fixture 100 includes one or more sensor(s) 118-119, which are configuredto measure distances to surfaces of spar 1902.

Generally, fixture 100 provides the ability to support, reposition, andsecure workpiece 200 in place for machining operations, therebyproviding a technical benefit over manually shimming parts, such as aspar for a wing of an aircraft. Fixture 100 therefore decreases themanual work and setup time that typically occurs during manuallyshimming parts prior to machining the parts, thereby improving theassembly process.

The embodiments of the disclosure may be described in the context of anaircraft manufacturing and service method 2000 as shown in FIG. 20 andan aircraft 2100 as shown in FIG. 21. During pre-production, exemplarymethod 2000 may include specification and design 2002 of aircraft 2100,and material procurement 2004. During production, component andsubassembly manufacturing 2006 and system integration 2008 of aircraft2100 takes place. Thereafter, aircraft 2100 may go through certificationand delivery 2010 in order to be placed in service 2012. While inservice by a customer, aircraft 2100 is scheduled for routinemaintenance and service 2014 (which may also include modification,reconfiguration, refurbishment, and so on).

Each of the processes of method 2000 may be performed or carried out bya system integrator, a third party, and/or an operator (e.g., acustomer). For the purposes of this description, a system integrator mayinclude without limitation any number of aircraft manufacturers andmajor-system subcontractors; a third party may include withoutlimitation any number of venders, subcontractors, and suppliers; and anoperator may be an airline, leasing company, military entity, serviceorganization, and so on.

As shown in FIG. 21, aircraft 2100 produced by exemplary method 2000 mayinclude an airframe 2102 with a plurality of systems 2104 and aninterior 2106. Examples of high-level systems 2104 include one or moreof propulsion systems 2108, an electrical system 2110, a hydraulicsystem 2112, and an environmental system 2114. Any number of othersystems may be included. Although an aerospace example is shown, theprinciples described in this specification may be applied to otherindustries, such as the automotive industry.

Apparatus and methods embodied herein may be employed during any one ormore of the stages of the production and service method 2000. Forexample, components or subassemblies corresponding to component andsubassembly manufacturing 2006 may be fabricated or manufactured in amanner similar to components or subassemblies produced while aircraft2100 is in service. Also, one or more apparatus embodiments, methodembodiments, or a combination thereof may be utilized during thecomponent and subassembly manufacturing 2006 and system integration2008, for example, by substantially expediting assembly of or reducingthe cost of aircraft 2100. Similarly, one or more of apparatusembodiments, method embodiments, or a combination thereof may beutilized while aircraft 2100 is in service, for example and withoutlimitation, to maintenance and service 2014.

FIG. 22 is an isometric view of fixture 100 in another illustrativeembodiment, and FIGS. 23-26 depicts fixture 100 of FIG. 22 duringvarious stages of operation. In this embodiment, base member 102 offixture 100 includes an upper portion 2202 coupled to a lower portion2204 by rails 2206. In this embodiments, rails 2206 allow upper portion2202 of base member 102 to translate on rails 2206 with respect to lowerportion 2204. For example, upper portion 2202 may translate to the rightin FIG. 22 in the direction of arrow 2208 or may translate to the leftin FIG. 22 in the direction of arrow 2210. In some embodiments, upperportion 2202 is free to slide back and forth in the directions of arrows2208-2210 while repositioning workpiece 200, which will be discussedbelow. In other embodiments, upper portion 2202 is driven in translationin the directions of arrows 2208-2210 by a drive mechanism 2212. Drivemechanism in may be used to augment the repositioning forces generatedby linear actuators 108-109 in some embodiments.

Prior to loading workpiece 200 onto fixture 100, outboard ends 114-115of linear actuators 108-109 are retracted towards their respective sides106-107 in order to ensure that contact members 112-113 and/or vacuumgrippers 116-117 are not damaged as workpiece 200 is loaded onto fixture100 (see FIG. 23). In FIG. 23, workpiece 200 is loaded onto fixtured 100such that centerline 220 of workpiece and indexing position 218 of basemember 102 are not coincident. Rather, centerline 220 of workpiece andindexing position 218 of base member 102 have offset 802 that isnon-zero and in particular, is larger than a threshold value. Such anon-zero offset 802 is due to the imprecise loading process of workpiece200 on fixture 100 and/or due to dimensional variations in workpiece 200from one part to another part. Vacuum source 228 may then be applied tovariable pressure grippers 120 to secure web 206 of workpiece 200 toupper portion 2202 of base member 102. As upper portion 2202 is free totranslate on rails 2206, floating web 206 on top surface 104 of upperportion 2202 by applying pressure source 230 to variable pressuregrippers 120 may be omitted. This is just one example in how fixture 100of FIG. 22 operates differently than fixture 100 of FIG. 1.

Processor 224 utilizes sensor 118 in order to measure distance 202 tosurface 232 of workpiece 200. Using distance 202, processor 224calculates offset 802 between centerline 220 of workpiece 200 andindexing position 218 of base member 102. For instance, memory 226 ofcontroller 222 may store pre-defined dimensional data for workpiece 200,which may be used by processor 224 to calculate offset 802 based on therelationship between distance 202 and the pre-defined dimensional datafor workpiece 200.

Offset 802 include both a displacement value and a direction ofdisplacement that depends on the frame of reference. In the followingdiscussion, the frame of reference is fixture 100, and in particularindexing position 218 of fixture 100. In FIG. 23, the direction ofoffset 802 of centerline 220 is to the left of indexing position 218,although the direction of offset 802 of centerline 220 may be to theright of indexing position 218 in other embodiments.

In response to calculating offset 802, processor 224 operates one ormore of linear actuators 108-109 to extend their vacuum grippers 116-117towards surfaces 232-233 of workpiece 200. Processor 224 may selectivelyoperate one or more linear actuators 108-109 in order to repositionworkpiece 200 on fixture 100 based on the direction of offset 802. Forexample, processor 224 may selectively operate linear actuators on acommon side depending on the direction of offset 802 of workpiece 200 onfixture 100. With offset 802 of centerline 220 being left of indexingposition 218 as illustrated in FIG. 23, processor 224 may elect tooperate linear actuator 108 alone in order to reposition workpiece 200on fixture 100 and/or may elect to operate both linear actuators 108-109in combination (e.g., by operating them in different combinations ofextension and retraction after their vacuum grippers 116-117 havegripped workpiece 200).

For the following discussion, FIGS. 24-26 will illustrate the use oflinear actuator 108 by itself for repositioning workpiece 200 on fixture100, although linear actuator 109 may also be used in a manner similarto those previously described for FIGS. 11-15.

In response to calculating offset 802 and selecting linear actuator 108,processor 224 extends outboard end 114 of linear actuator 108 asillustrated in FIG. 24 in the direction of arrow 902, thereby movingvacuum gripper 116 into contact with surface 232 of workpiece 200. Withvacuum gripper 116 in contact with surface 232, processor 224 directsvacuum source 228 to apply a vacuum to vacuum gripper 116. For example,processor 224 may operate one or more valves to apply vacuum source 228to vacuum gripper 116. With vacuum applied to vacuum gripper 116, vacuumgripper 116 grips surface 232 of workpiece 200, although step 408 may beoptional when a grip of workpiece 200 is not necessary (e.g., whenlinear actuator 108 can reposition workpiece 200 on fixture 100 withouta grip on workpiece 200).

Processor 224 continues to extend outboard end 114 of linear actuator108 in the direction of arrow 902 to move workpiece 200 in the directionof arrow 1002, as illustrated in FIG. 25. In some embodiments, movingworkpiece 200 may be augmented using drive system 2212 (see FIG. 22),which drives upper portion 2202 of base member 102 in the same directionas arrow 902. In other embodiments, upper portion 2202 is free totranslate on rails 2206 (see FIG. 22) without the use of drive mechanism2212.

As processor 224 continues to extend outboard end 114 of linear actuator108 in the direction of arrow 902 (and/or drive mechanism 2212 drivesupper portion 2202 in the direction of arrow 2208), workpiece 200continues to move in the direction of arrow 1002 until offset 802 isless than a threshold value, thereby effectively repositioning workpiece200 on fixture 100 as illustrated in FIG. 26. With workpiece 200repositioned on fixture 100, processor 224 may then extend outboard end115 of linear actuator 109 in the direction of arrow 1202 to extendvacuum gripper 117 until vacuum gripper 117 contacts surface 233 ofworkpiece 200, and apply a vacuum to vacuum gripper 117 to secureworkpiece 200 to fixture 100. With workpiece 200 secured to fixture 100,robotic end mill 210 (see FIG. 2) may utilize end effector 214 toperform one or more machining operations on workpiece 200.

The use of upper portion 2202 in this embodiment that translates onrails 2206 reduces the preload applied to workpiece 200 when workpiece200 is repositioned.

FIG. 27 is a block diagram of fixture 100 depicted in FIG. 22 in anillustrative embodiment. As FIG. 27 is similar to FIG. 19, only thedifferences between the two figures will be discussed. In FIG. 27, upperportion 2202 of base member 102 includes variable pressure grippers 120proximate to top surface 104, which supports spar 1902. Rails 2206couple upper portion 2202 with lower portion 2204 of base member 102,with optional drive mechanism 2212 used to augment the movement of upperportion 2202 in some embodiments.

Any of the various elements shown in the figures or described herein maybe implemented as hardware, software, firmware, or some combination ofthese. For example, an element may be implemented as dedicated hardware.Dedicated hardware elements may be referred to as “processors”,“controllers”, or some similar terminology. When provided by aprocessor, the functions may be provided by a single dedicatedprocessor, by a single shared processor, or by a plurality of individualprocessors, some of which may be shared. Moreover, explicit use of theterm “processor” or “controller” should not be construed to referexclusively to hardware capable of executing software, and mayimplicitly include, without limitation, digital signal processor (DSP)hardware, a network processor, application specific integrated circuit(ASIC) or other circuitry, field programmable gate array (FPGA), readonly memory (ROM) for storing software, random access memory (RAM),non-volatile storage, logic, or some other physical hardware componentor module.

Also, an element may be implemented as instructions executable by aprocessor or a computer to perform the functions of the element. Someexamples of instructions are software, program code, and firmware. Theinstructions are operational when executed by the processor to directthe processor to perform the functions of the element. The instructionsmay be stored on storage devices that are readable by the processor.Some examples of the storage devices are digital or solid-statememories, magnetic storage media such as a magnetic disks and magnetictapes, hard drives, or optically readable digital data storage media.

Although specific embodiments were described herein, the scope is notlimited to those specific embodiments. Rather, the scope is defined bythe following claims and any equivalents thereof

What is claimed is:
 1. A tooling fixture, comprising: a base member; agripper assembly, comprising: a linear actuator coupled to a side of thebase member and having an outboard end that is linearly movable by thelinear actuator; a vacuum gripper located at the outboard end of thelinear actuator; and a sensor configured to measure a distance to asurface of a workpiece disposed on the base member; and a controllerconfigured to calculate an offset between an indexing position on thebase member and a centerline of the workpiece based on a distance to thesurface of the workpiece, and to move the vacuum gripper relative to theside of the base member into contact with the surface of the workpieceutilizing the linear actuator, the controller configured to apply avacuum to the vacuum gripper to grip the surface of the workpiece, andto reposition the workpiece on the base member utilizing the linearactuator until the offset is less than a threshold value.
 2. The toolingfixture of claim 1, further comprising: at least one variable pressuregripper along a top surface of the base member, wherein the controlleris configured to apply a positive pressure to the variable pressuregripper to form a film of air between the top surface of the base memberand a surface of the workpiece in contact with the top surface of thebase member.
 3. The tooling fixture of claim 2, wherein: the controller,in response to the offset being less than the threshold value, isconfigured to apply a vacuum to the variable pressure gripper to gripthe surface of the workpiece in contact with the top surface of the basemember.
 4. The tooling fixture of claim 1, wherein: the controller, inresponse to the offset being less than the threshold value, isconfigured to lock movement of the linear actuator to secure theworkpiece to the base member.
 5. The tooling fixture of claim 1,wherein: the gripper assembly comprises a first gripper assembly, thetooling fixture further comprises a second gripper assembly coupled to aside of the base member opposite the first gripper assembly.
 6. Thetooling fixture of claim 5, wherein: the controller is configured tooperate the linear actuators of the first and second gripper assembliesto linearly move the vacuum grippers relative to sides of the basemember into contact with opposing surfaces of the workpiece, to apply avacuum to the vacuum grippers to grip the opposing surfaces of theworkpiece, and to utilize the sensors of the first and second gripperassemblies to measure distances to the opposing surfaces of theworkpiece, the controller configured to determine the offset between theindexing position on the base member and the centerline of the workpiecebased on the distances, and to reposition the workpiece on the basemember utilizing the linear actuators until the offset is less than thethreshold value.
 7. The tooling fixture of claim 1, further comprising:a contact member located at the outboard end of the linear actuator. 8.The tooling fixture of claim 1, wherein the base member comprises: anupper portion proximate to the workpiece; a lower portion; and at leastone rail slidably coupling the upper portion to the lower portion,wherein the controller is configured to reposition the workpiece on thebase member utilizing the linear actuator to slide the upper portion onthe rails until the offset is less than a threshold value.
 9. Thetooling fixture of claim 8, further comprising: a drive mechanismconfigured to drive the upper portion on the rails with respect to thelower portion, wherein the controller is configured to reposition theworkpiece on the base member utilizing the linear actuator and the drivemechanism to drive the upper portion on the rails until the offset isless than a threshold value.
 10. A tooling system, comprising: aplurality of tooling fixtures disposed in a common indexing line andconfigured to hold a workpiece along its length, each of the toolingfixtures comprising: a base member; a gripper assembly, comprising: alinear actuator coupled to a side of the base member and having anoutboard end that is linearly movable by the linear actuator; a vacuumgripper located at the outboard end of the linear actuator; and a sensorlocated on the side of the base member that is configured to measure adistance to a surface of the workpiece; and a controller configured tocalculate a deflection of a centerline of the workpiece with respect tothe common indexing line on the tooling fixtures based on a plurality ofdistances measured by the sensors, and to operate the linear actuatorsto linearly move the vacuum grippers relative to the sides of the basemembers into contact with the surfaces of the workpiece, the controllerconfigured to apply a vacuum to the vacuum grippers to grip the surfacesof the workpiece, and to reposition the workpiece on the base membersutilizing the linear actuators until the deflection is less than athreshold value.
 11. The tooling system of claim 10, wherein each of thetooling fixtures further comprises: at least one variable pressuregripper along a top surface of the base member, wherein the controlleris configured to apply a positive pressure to the variable pressuregrippers to form a film of air between the top surfaces of the basemembers and a surface of the workpiece in contact with the top surfacesof the base members.
 12. The tooling system of claim 11, wherein: thecontroller, in response to the deflection being less than the thresholdvalue, is configured to apply a vacuum to the variable pressure grippersto grip the surface of the workpiece in contact with the top surfaces ofthe base members.
 13. The tooling system of claim 10, wherein: thecontroller, in response to the deflection being less than the thresholdvalue, is configured to lock movement of the linear actuators to securethe workpiece to the base members.
 14. The tooling system of claim 10,wherein: the gripper assembly comprises a first gripper assembly, eachof the tooling fixtures further comprises a second gripper assemblycoupled to a side of the base member opposite the first gripperassembly.
 15. The tooling system of claim 14, wherein: the controller isconfigured to operate the linear actuators of the first and secondgripper assemblies of the tooling fixtures to linearly move the vacuumgrippers relative to sides of the base member into contact with opposingsurfaces of the workpiece, to apply a vacuum to the vacuum grippers togrip the opposing surfaces of the workpiece, and to utilize the sensorsof the first and second gripper assemblies to measure distances to theopposing surfaces of the workpiece, the controller configured todetermine the deflection of the centerline of the workpiece with respectto the common indexing line based on the distances, and to repositionthe workpiece on the base members utilizing the linear actuators untilthe deflection is less than the threshold value.
 16. The tooling systemof claim 10, wherein the gripper assembly further comprises: a contactmember located at the outboard end of the linear actuator.
 17. Thetooling system of claim 10, wherein the base member comprises: an upperportion proximate to the workpiece; a lower portion; and at least onerail slidably coupling the upper portion to the lower portion, whereinthe controller is configured to reposition the workpiece on the basemembers utilizing the linear actuators to slide the upper portions onthe rails until the deflection is less than a threshold value.
 18. Thetooling system of claim 17, further comprising: a drive mechanismconfigured to drive the upper portion on the rails with respect to thelower portion, wherein the controller is configured to reposition theworkpiece on the base members utilizing the linear actuators and thedrive mechanisms to drive the upper portions on the rails until thedeflection is less than a threshold value.
 19. A method operating atooling fixture, the method comprising: loading a workpiece on a toolingfixture, wherein the tooling fixture comprises a base member, a linearactuator coupled to a side of the base member and having an outboard endthat is linearly movable by the linear actuator, a vacuum gripperlocated at the outboard end, and a sensor located on the side of thebase member that is configured to measure a distance to a surface of theworkpiece disposed on the base member; calculating an offset between anindexing position on the base member and a centerline of the workpiecebased on a distance measured to the surface of the workpiece utilizingthe sensor; operating the linear actuator to move the vacuum gripperrelative to the side of the base member into contact with the surface ofthe workpiece; applying a vacuum to the vacuum gripper to grip thesurface of the workpiece; and repositioning the workpiece on the basemember utilizing the linear actuator until the offset is less than athreshold value.
 20. The method of claim 19, wherein the tooling fixtureincludes at least one variable pressure gripper along a top surface ofthe base member, wherein repositioning the workpiece further comprises:applying a positive pressure to the variable pressure gripper to form afilm of air between the top surface of the base member and a surface ofthe workpiece in contact with the top surface of the base member. 21.The method of claim 20, further comprising: applying a vacuum to thevariable pressure gripper to grip the surface of the workpiece incontact with the top surface of the base member in response to theoffset being less than the threshold value.
 22. The method of claim 19,further comprising: locking movement of the linear actuator to securethe workpiece to the base member in response to the offset being lessthan the threshold value.